Authorities were still investigating both attacks early Tuesday. Authorities in German called the truck attack at a Berlin Christmas market that left 12 dead and nearly 50 injured a suspected “terror attack.” The White House had already described the attack as an apparent terrorist attack as well.

Trump said the Islamic State group "and other Islamist terrorists continually slaughter Christians in their communities and places of worship as part of their global jihad."

Trump called the assassination of the Russian ambassador to Turkey at a photo exhibit “a violation of all rules of civilized order.” He added that a “radical Islamic terrorist” had assassinated the diplomat Adrew Karlov.

He added that these terrorists and their regional and worldwide networks "must be eradicated from the face of the earth" and pledged to carry out that mission with "all freedom-loving partners."

He later tweeted: "Today there were terror attacks in Turkey, Switzerland and Germany — and it is only getting worse. The civilized world must change thinking!"

In Zurich, police said three people were wounded when a gunman opened fire in the prayer hall of a mosque frequented by Somali immigrants.

Trump vowed during the presidential campaign to go after the Islamic State group, but repeatedly declined to fill in the public on his plan.

Trump’s statements coincided with the Electoral College certifying his victory, clearing the way for his Jan. 20 inauguration.

Trump also announced his candidate for secretary of the Army on Monday and held a round of transition meetings.

He was expected to hold additional transition meetings at his Palm Beach, Florida, estate on Tuesday and Wednesday.

His choice of Army veteran and fellow New Yorker Vincent Viola to be Army secretary will put another billionaire in a leading role in the new administration. Viola is a West Point graduate who joins a list of individuals with military backgrounds already bound for the Cabinet. Trump's picks for defense secretary, homeland security secretary, national security adviser and deputy national security adviser are retired military.

Viola was the first member of his family to attend college. He was trained as an Airborne Ranger infantry officer and served in the 101st Airborne Division. A lawyer, he started multiple businesses, became a billionaire and bought the Florida Panthers hockey team for $250 million in 2013.

Trump has already tapped several wealthy businessmen for jobs, including fast-food executive Andy Puzder to be secretary for the Labor Department, billionaire investor Wilbur Ross for Commerce, financier Steven Mnuchin for Treasury and Goldman Sachs President Gary Cohn as his top economic adviser.

Trump still has numerous other posts to fill, including U.S. trade representative. Among those he met with on Monday at his Mar-a-Lago estate was Robert Lighthizer, a deputy U.S. trade representative in the Reagan administration, Trump's aides said.

Trump is spending the run-up to Christmas with his family.

The president-elect also had dinner Saturday at the Florida club with Mexican billionaire Carlos Slim, a surprising development given Trump's harsh criticism of Slim during the presidential election. Slim is a major investor in The New York Times, which is also a frequent Trump target.

Neither did Slim spare Trump, who has criticized Mexicans and vowed to build a wall between the U.S. and Mexico to stop illegal immigration.

Representatives for Trump and Slim confirmed the dinner, which was first reported Monday by The Washington Post.

People briefed on the meeting said it was arranged to open a friendly line of communication between the businessmen. The dinner was brokered by former Trump campaign manager Corey Lewandowski, who remains close to the president-elect, after Lewandowski quietly visited Slim in Mexico City earlier this month.